Methane is a primary constituent of landfill gas (LFG) and a potent contributor to greenhouse gasses. MSWF are the largest source of human-related (anthropogenic) methane emissions in the United States. In 2004, for example, MSWF accounted for about 25 percent of the methane emissions in the United States. Additionally, escaping LFG emissions are a lost opportunity to capture and use a significant energy source. Substantial economic and environmental benefits are achieved by capturing LFG prior to release, while subsequently reducing greenhouse gasses. LFG capture projects improve energy independence while lowering energy costs, contribute to the creation of jobs, and help local economies. LFG is currently recovered from landfills using a series of wells and a vacuum system that consolidates the collected gas for transportation and processing. LFG is then used for a variety of purposes including, but not limited to, motor vehicle fuel, generator fuel, biodiesel production, natural gas supplement, as well as and a green power source.
Currently, MSWF bury waste in layers in excavations over time (See FIG. 1A). The basic structure is a floor and sidewalls of compacted clay, typically covered with a high density polyethylene (HDPE) polymer liner, filled with layers of waste alternated with clay or soil layers covering the waste layers (See FIG. 1B). Once a landfill has reached a certain capacity, LFG recovery wells are installed and LFG is extracted from the decay and decomposition of waste layers. The original pipe which is placed in the LFG recovery well has a perforated end so that LFG can be recovered. The perforated end is sometimes referred to as a screen section. The perforated end or screen section may have holes drilled into it or slots cut into it. As the waste in the landfill increases in height, non-apertured “riser pipe”, “pipe”, “casing”, “riser”, “extended riser”, or “vertical pipe” is added to the existing well. These terms may be used interchangeably for the tubular members extending into the waste body and includes tubular members that are perforated to form a screen section. Once the waste body reaches the design height or capacity it is covered with compacted soil, topsoil, or in some cases liner material and the surface is subsequently replanted with natural vegetation and the waste body left to decompose. LFG is created as the organic fraction of solid waste decomposes in a landfill. LFG consists of about 50 percent methane (CH4), the primary component of natural gas, about 40-49% percent carbon dioxide (CO2), and a small amount of non-methane organic compounds. Landfills must be monitored over time to ensure that LFG emissions, leachate, and waste from the solid waste unit are not being released and impacting the environment. Methane extraction and recovery captures LFG and prevents or decreases emission of these air contaminants. LFG is first produced in the older, lower levels of decomposing waste bodies. Subsequent layers of waste produce LFG at different times and rates. Currently, to recover LFG from these additional layers, wells are drilled to a desired depth or elevation and LFG is extracted using a vacuum system. If not captured, the LFG escapes through the landfill cap and into the atmosphere. As decomposition continues, shallower wells are required to capture LFG generated in the upper waste bodies (See FIG. 1C). This is currently accomplished by the advancement of new wells into the upper waste bodies, which can be a capital intensive process.
Captured LFG can be used for energy generation to produce electricity with engines, turbines, microturbines, or similar technologies. LFG is also used as an alternative to fossil fuels and can be refined and injected into a natural gas pipeline. The capture and application of LFG in these ways yields substantial energy, economic, environmental, and public health benefits. Internationally, significant opportunities exist for the expansion and increase of LFG recovery and use while reducing harmful emissions of greenhouse gases. LFG recovery and use is a reliable and renewable fuel option that represents a largely untapped and environmentally friendly energy source at thousands of landfills in the United States and abroad.
Traditional attempts to enter non-functional or under-producing methane recovery wells for rehabilitation purposes have been unsuccessful for many various reasons. For example, such wells are often on side slopes or uneven ground which makes access to the wells with traditional equipment (i.e. a drill rig) very difficult and sometimes impossible. Additionally, the pipes used for such wells in MSWF are made from a material that often bends and deviates after well installation and during waste placement resulting in wells that are no longer vertical. This makes traditional re-entry attempts very difficult. Couplers, lag screws, or similar type fasteners used to connect additional pipes or risers generate obstructions inside the wells, making re-entry near impossible at depths necessary for successful well rehabilitation. These reasons among others severely limit the available methods to successfully rehabilitate a methane gas recovery well. Since at least 1993, the need to rehabilitate existing LFG recovery wells has been a recognized unsolved problem. An internal pipe aperture tool and a method of use is needed to successfully re-enter and rehabilitate flooded, clogged, obstructed, and otherwise rendered inoperable LFG recovery wells as well as adding apertures to riser pipe that has been added on to existing LFG recovery wells.